Development of Ultra-high Density Three-dimensional Optical Data storage System

诸如CD和DVD的光学数据存储系统现在被广泛使用。然而，这种当前可用的存储系统的容量不足以以高质量记录电影，即使存储密度几乎达到理论极限。因此，需要新的数据存储系统。我们研制了以二氧化硅为记录材料的三维光数据存储系统，并阐明了以下几点：1。利用皮秒或飞秒单脉冲辐照，通过多光子过程在一个小区域（称为“比特”）内引起折射率的变化。利用这种效应，可以构建三维数据存储系统.产生比特的时间周期约为400 ps。3.在钻头中心产生一个小的凹陷。该钻头具有极高的热稳定性，在1150 ℃退火后，光学显微镜图像无变化.这些碎片显示出特定的发光光谱。热退火降低了发光强度，500 ℃退火后发光性能几乎丧失.对于多层记录的样品，通过透射和发光图像两者独立地读取每一层。在其他材料如PMMA中，发现了相同的效果。

Optical data storage systems, such as CD and DVD, are now widely used. However, capacity of such currently available storage systems are not enough for recording movies in a high-quality even the storage densities are almost reaching to the theoretical limit. Accordingly a new data storage system is required. We have developed three-dimensional (3D) optical data storage system using silica as recording material, and clarified the following points :1. By irradiation of picosecond or femtosecond single pulse, a change in reflactive index is induced in a small domain (reffered as "bit") through a multiphoton process. Using such an effect, a three-dimensional data storage system can be constructed.2. The time-period to generate a bit was about 400 ps.3. A small hollow was generated at the center of the bit.4. The bits are thermally stable extremely ; by annealing at 1150 degree no change was induced in optical microscope image.5. The bits showed a specific luminescence spectra. The luminescence intensity was reduced by thermal annealing ; by annealing at 500 degree the luminescent property was almost lost.6. For multi-layer recorded samples, each layer was independently read by both transmission and luminescence images.7. In the other materials such as PMMA, the same effect was found.